docs: def check_valid_device(self, path, run_as_root=True):
          """Verify an existing RBD handle is connected and valid."""
          if self.im_root:
              try:
                  with open(path, 'r') as f:
                      f.read(4096)
              except Exception:
                  return False
              return True
  
          try:
              self._execute('dd', 'if=' + path, 'of=/dev/null', 'bs=4096',
                            'count=1', root_helper=self._root_helper,
                            run_as_root=True)
          except putils.ProcessExecutionError:
              return False
          return True